CORDILLERA'S RIVER SYSTEMS

The Cordillera is dubbed as the watershed cradle of Northern Luzon. Its forests sustain six of Northern Luzon's major river systems. Perhaps because of this, government classifies 85% of the region as forestland. Of this, 30% is officially designated as forest reserve.

The Mount Data forest reserve, located along the Benguet-Mountain Province boundary, hosts the headwaters of five major rivers that traverse the Cordillera provinces and drain into the lowlands.

The most extensive of these is the Chico River, which cuts through Mountain Province into Kalinga, where it is fed by the Tanuda, Pasil, and Saltan rivers. From Kalinga, it flows into Cagayan province where it drains into the Rio Grande de Cagayan.

The Ahin River flows eastward from Mt. Data, through the province of Ifugao, where it is joined by the Ibulao river before it empties into the Magat river along the Ifugao-Isabela border.

The Siffu River, another Magat tributary, originates from eastern Mountain Province, cuts through Ifugao, then drains into Magat in Isabela.

The Abra River flows westward from Mt. Data, descends to Cervantes, Ilocos Sur, and flows to the province of Abra, where it is joined by the Tineg River, which originates from the Abra uplands. It exits Abra and cuts through Ilocos Sur before emptying into the South China Sea.

The Amburayan River flows southwestward from Mt. Data, traverses western Benguet, then drains into La Union, where it is fed by the Naguilian and Aringay rivers that also originate in Benguet, then empties into the South China Sea.

Also from Mt. Data, the Agno River flows southward through eastern Benguet, then drains into Pangasinan. Here it takes a westerly course, swings back north, and then drains into Lingayen Gulf. Agno has numerous tributaries, the largest of which is the Bued River. (For details of the Ambuklao, Binga and San Roque dams across the Agno, see section on Dams.)

Farthest north in the Cordillera region are the twin rivers, Abulug River and Apayao River, both originating from the province of Apayao. They meet near Kabugao municipality and from there drain to the sea.

Cordillera's river basins have enormous water-bearing capacity. They have a total drainage area of 5,447,500 hectares and groundwater storage of about 150 million cubic meaters. Government planners say this is more than enough for supplying the irrigation and energy needs of entire Northern Luzon.

See also: Cordillera's forest resources, hydropower generation.